This same study of tamoxifen users concluded that rs3740065(T;T) patients who also had two CYP2D6 risk alleles had a 45 fold higher risk of recurrence than patients with zero or one (out of the possible four) risk alleles. The overall average recurrence risk was 5x for carriers of a total of two risk alleles, and 20x for carriers of a total of three risk alleles.[PMID 20124171]

A nearby SNP, rs11190303, also showed significant association to recurrence-free survival; it was shown to be strongly linked to rs3740065 (r2 with LD of 0.79).[PMID 20124171]